At the 2004 Athens Olympics Zhou reached the semifinal round where she was eliminated from gold medal contention by fellow countrywoman Zhang Ning.

[2][3] His rationale was that a fresh Zhang Ning would have a better chance to defeat a non-Chinese opponent, the Netherlands' Mia Audina, in the final.

Whether the Olympic episode or subsequent injury and poor performance was the primary cause, Zhou apparently retired from badminton during the 2005 season.

[4] From a weak start at the Singapore Open her results dramatically improved to the point where she had regained a number one world ranking as of the end of the year 2008.

In December, Zhou ended the 2008 season by winning the BWF Super Series Masters Finals, the biggest prize money event in the sport.

Zhou tested positive to clenbuterol, a Class 1 Anabolic Agent on the WADA Prohibited List of substances.

[6] On 27 October 2011, more than one year after she was handed a two-year ban for testing positive for clenbuterol, former badminton world No.